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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 47 (1995), S. 0 
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: American plaice held in captivity for a period of 8 months over winter exhibited increasing erythrocyte osmotic fragility and decreasing haematocrit values until December. In December, osmotic fragility parameters and haematocrit were strongly correlated, suggesting anaemia due to disruption of circulating erythrocytes. Intensity of infection with Haemohormidium terranovae increased through the winter months until March but was not correlated either with osmotic fragility or haematocrit. These results are explained in terms of compensatory haemopoetic changes occurring in plaice. Mortality was apparently unrelated to any of the parameters investigated.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1365-2761
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Abstract. Pale and swollen gills were observed in 23 of 240 Laval's eelpouts, Lycodes lavalaei Vladykov and Tremblay (Perciformes), taken from several locations off the coasts of Newfoundland and southern Labrador. Light microscopic study of histological sections revealed clusters of unidentified cells (‘X-cells’) in the basal region of secondary gill lamellae and extending along the latter, between the epithelium and lamellar capillaries. In the electron microscope two types of X-cells were enclosed in a network of cytoplasmic processes from dense ‘envelope’ cells. Both types of X-cells were bound by a densely-coated limiting membrane and had nuclei with large, dense nucleoli, numerous mitochondria with short vesicular cristae, lipid inclusions, abundant smooth endoplasmic reticulum and small dense inclusions. The Type II X-cells were larger, contained a much greater concentration of lipid and small dense inclusions, and an additional inclusion with a dense core surrounded by a light halo. The X-cells are compared with strikingly similar cells described from epidermal and pseudobranch tumours of marine fish. Although transformation of a host cell by virus or possibly pollution has been suggested, neither the nature nor the origin of the X-cells can be determined.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The sporogonic and merogonic development of Babesiosoma stableri Schmittner & McGhee, 1961 within its definitive host and vector, a leech Batracobdella picta (Verrill, 1872), was studied by light and electron microscopy. Gamonts released from frog erythrocytes in the blood meal of the leech associated in syzygy and fused; the gamonts were isogamous and only 1 microgamete was formed. The ultrastructural appearance of the resulting zygote was similar to that of the gamonts, but it was larger. The zygote had an apical complex (including a polar ring, conoid and 2 pre-conoidal rings and micronemes, but no recognizable rhoptries), triple-membraned pellicle, about 40 subpellicular microtubules and prominent stores of amylopectin. Zygotes penetrated the cells of the intestine and underwent sporogony directly within the cytosplasm of the ieech epithelial cell without the formation of a parasitophorous vacuole. Eight sporozoites budded simultaneously around the periphery of an irregularly shaped oocyst. No oocyst wall was formed. Each sporozoite had a complete apical complex (including rhoptries), abundant amylopectin inclusions and a triple-membraned pellicle with about 32 subpellicular microtubules. The sporozoites initiated merogonic replication primarily within the salivary cells of the leech although other tissues, such as muscle, were infected. Each meront produced 4 merozoites by simultaneous budding, forming a cruciform meront typical of the intraerythrocytic development of this parasite. The meront was located directly within the cytoplasm of the host cell. Merozoites, with abundant amylopectin, had a complete apical complex and triple-membraned pellicle with about 40 subpellicular microtubules. The merozoites either initiated a further cycle of replication, or they moved into the ductules of the leech salivary cells which extend to the tip of the proboscis. Observations on gametogenesis. syngamy and sporogony of B. stableri in its leech host indicate that the family Dactylosomatidae should be placed in the suborder Adeleina (Eucoccidiida: Apicomplexa). Babesiosoma stableri was transmitted to uninfected frogs (Rana spp.) by the bite of infected leeches. Prepatent periods ranged from 26 to 38 days at 25° C. Despite a directed search in laboratory reared tadpoles which had each been injected intraperitoneally with 150,000 merozoites, no pre-erythrocytic developmental stages were observed. Similarities in their biology suggest close phylogenetic affinities of the dactylosomatids, and other adeleid blood parasites, with the piroplasms of higher vertebrates.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 35 (1988), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . Mature gamonts of Haemogregarina magna lie within a type of parasitophorous vacuole (Pv) apparently unique to the haemogregarines. The cytoplasm of infected erythrocytes was separated from the parasite by two Pv membranes. An additional membrane, coated on both sides with electron-dense material, closely invested the gamonts. The apical complex of the gamonts includes a conoid, two preconoidal rings, and an elaborate polar ring complex. The latter consisted of the polar ring and approximately 78 posteriorly directed, radially arranged, “tine-like” structures which fuse as they merge anteriorly into the polar ring. Freeze fracture replicas demonstrated that the pellicle of gamonts of H. magna was structurally similar to that of other apicomplexans. The closely apposed inner membranes of the pellicle formed plates which were arranged into strips along the long axis of the gamont. Calculations indicated that 13 such strips are found around the circumference of the gamonts with about six subpellicular microtubules associated with the inner surface of each strip. Gamonts of H. magna share many structural similarities with the kinetes, ookinetes, and sporokinetes of other apicomplexans. We propose that the conoid and polar ring complex are fundamental features of all apicomplexan “kinetes.”
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 18 (1971), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SYNOPSIS. Single megaloschizonts give rise to elongate and round gametocytes, the former outnumbering the latter. Male and female elongate gametocytes develop from merozoites of a single megaloschizont. Elongate gametocytes were seen 2–7 days and round gametocytes 6–11 days after megaloschizonts had been inoculated into ducklings. Experimental evidence indicates that merozoites of megaloschizonts invade blood cells and develop into elongate gametocytes. Other merozoites infect tissue cells and develop into secondary exoerythrocytic schizonts which give rise to round gametocytes. Relapse in Leucocytozoon simondi infections is discussed in relation to megaloschizont-induced exoerythrocytic schizogony.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Comparative clinical pathology 2 (1992), S. 75-78 
    ISSN: 1433-2981
    Keywords: Bleeding ; Fish ; Frog ; Haemostasis ; Hirudin ; Leech ; Platelet ; Thrombocyte
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The bite of the North American leech Macrobdella decora results in much less prolonged bleeding in fish (8 min; control = 1 min) and amphibians (11.5 min; control = 1.5 min) than in mammals (humans) (73 min; control = 6 min). Coagulation of blood flowing from leech bite wounds is initially prolonged in frogs (4.3 min; control = 2 min) and humans (5.8 min; control = 2.5 min), but gradually returns to normal during the first 10 min after the termination of feeding. Although duration of feeding is similar in fish (mean = 62 min), amphibian (mean = 79 min) and human (mean = 68 min) hosts, the gain in body weight of leeches feeding on fish (mean = 11%) and amphibians (mean = 14%) is much less than those feeding on humans (mean = 58%). Bleeding in a frog heavily infected with the intrathrombocytic yeast Thrombocytozoons ranarum was abnormal from control incisions (〉20 min) and from a leech bite wound (〉140 min) suggesting impairment of thrombocyte function. This comparative approach to leech — host haematology offers a methodology into understanding the biological context in which the leech antithrombin (hirudin) evolved, as well as the evolution of vertebrate haemostatic mechanisms.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Systematic parasitology 33 (1996), S. 33-51 
    ISSN: 1573-5192
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract During 1992, the cloaca of 83 specimens of North American Amphibia from Algonquin Park and Kingston, Ontario, Canada, and from El Paso County, Texas, USA, comprising 14 species in seven families, were checked for opalinids.Opalina martinonae n. sp. was found in five of nineRana sylvatica (Ranidae);O. obtrigonoidea Metcalf, 1923 in six of 11Bufo americanus (Bufonidae) and two of ninePseudacris crucifer (Hylidae);O. pickeringi Metcalf, 1923 in two of ninePseudacris crucifer and in one of sixRana pipiens; andO. virguloidea Metcalf, 1923 in two of sixHyla versicolor (Hylidae).Opalina flava Stokes, 1884 is proposed forCepedea flava (Stokes, 1884) Metcalf, 1923. The occurrence, evolution and biogeography of North AmericanOpalina are discussed.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Systematic parasitology 32 (1995), S. 141-147 
    ISSN: 1573-5192
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract During 1992, 83 specimens of North American Amphibia from Algonquin Park and Kingston, Ontario, Canada, and from El Paso County, Texas USA, comprising 14 species in seven families, were checked for opalinids in the cloaca.Protoopalina allisteri n. sp. is described from oneGastrophryne carolinensis (Microhylidae) from Arkansas andP. mitotica was found in one of fourScaphiopus multiplicatus (Pelobatidae) from Texas. The North American species ofProtoopalina are reviewed.Zelleriella ovoidea (Metcalf, 1923) is proposed as a new combination forP. ovoidea.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Systematic parasitology 33 (1996), S. 33-51 
    ISSN: 1573-5192
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract During 1992, the cloaca of 83 specimens of North American Amphibia from Algonquin Park and Kingston, Ontario, Canada, and from El Paso County, Texas, USA, comprising 14 species in seven families, were checked for opalinids. Opalina martinonae n. sp. was found in five of nine Rana sylvatica (Ranidae); O. obtrigonoidea Metcalf, 1923 in six of 11 Bufo americanus (Bufonidae) and two of nine Pseudacris crucifer (Hylidae); O. pickeringi Metcalf, 1923 in two of nine Pseudacris crucifer and in one of six Rana pipiens; and O. virguloidea Metcalf, 1923 in two of six Hyla versicolor (Hylidae). Opalina flava Stokes, 1884 is proposed for Cepedea flava (Stokes, 1884) Metcalf, 1923. The occurrence, evolution and biogeography of North American Opalina are discussed.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-1955
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The life cycle ofHepatozoon sipedon sp. nov. was studied in two snake species, the Northern water snake and the Eastern garter snake, in its mosquito hostsCulex pipiens andC. territans, and in the Northern leopard frog. Gametogenesis, fertilization and sporogony occurred within fat body cells in the haemocoel of mosquitoes that had fed on infected water snakes. Mature oocysts averaging 263 μm in diameter and containing more than 500 sporocysts were observed in mosquitoes 28 days post-feeding. Each sporocyst enclosed eight sporozoites. Dizoic cysts were found in the liver of frogs that had been fed infected mosquitoes seven days previously. Two rounds of merogony in various internal organs and intraerythrocytic gamonts were observed in snakes that had been fed frogs which had been orally inoculated with infected mosquitoes. Developmental stages were not seen in snakes that were fed infected mosquitoes directly. A comparison of this life cycle with those described for otherHepatozoon species infecting snakes is presented with reference to the different modes of transmission featured by these parasites.
    Type of Medium: Electronic Resource
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